A conventional so-called junction box is constructed as shown, for example, in the fragmentary sectional view of FIG. 15. Various electronic elements as electronic parts 21 are mounted on a board 26, and terminals 22 are projected out from the peripheral edge of the board 26. The board 26, including the electronic parts 21, is electrically insulated with insulators 23 and 24 and thereafter housed in a box made of a synthetic resin. The junction box comprises a casing 25. Each terminal 22 projects out in a part of the peripheral edge of the casing 25. After the board 26 and so forth have been attached to the bottom of the casing 25, a lower cover 27 is attached to the casing 25 with the insulator 24 interposed between the lower cover 27 and the board 26. The lower cover 27 is provided with heat-radiating members 27a, e.g. fins.
The top of the casing 25 corresponds to the side of the board 26 on which the electronic parts 21 are mounted. The top of the casing 25 constitutes an opening. An upper cover 28 is installed in the opening on the top of the casing 25. The casing 25, the upper cover 28 and the lower cover 27 are usually molded pieces produced by injecting a synthetic resin. The board 26 is electrically insulated when installed in the casing 25. The joint of each cover and the casing 25 is waterproofed to prevent entry of water, etc. Conventionally, sealing has been provided for the prevention of entry of water, etc.
The following methods are publicly known as examples of waterproofing techniques for connection boxes such as the above-described prior art junction box. In one method, the joint surfaces of the casing and the cover are provided with ribs, and the casing and the cover are interlocked with each other to effect waterproofing. In another method, a part of the electrical connection box is provided with a partition wall for leading in electric wires, thereby preventing entry of water into the electrical component housing box.
As has been stated above, the conventional junction boxes are in the form of boxes housing electrical components. Most of them are casings molded of a synthetic resin or the like. In a typical type of conventional junction box, electronic parts are housed in such a casing, and terminals are projected out of the casing. Alternatively, electric wires are led out of the casing. Then, covers are attached to the casing. The casing molded of a synthetic resin or the like is a member separate from the covers. The structure of the casing tends to become complicated in view of waterproofing measures, connection of terminals and electric wires, etc.
In addition, covers are indispensable because electronic parts have to be housed afterward. For this reason, the conventional junction box is structured by taking waterproofing measures into consideration as stated above. In consequence, the conventional junction box suffers from the problems that the casing itself becomes large in size, and the weight and cost also increase. In the case of the engine room of an automobile, vibration and noise prevention measures must be taken into consideration in addition to waterproofing because running is involved. Automobiles now tend to be lighter in weight, and developments and efforts have been made to achieve lightweight structures for vehicle bodies and engines. In this regard, junction boxes are also not exceptions.
With the above-described technical background, the present invention was made to attain the following objects.
An object of the present invention is to provide electrical equipment for junction, which is conventionally known as a “junction box”, wherein a board having electronic parts mounted thereon is integrally sealed and covered with covers, thereby achieving reductions in size and weight of the electrical equipment, and also provide a method of manufacturing the electrical equipment for junction.
Another object of the present invention is to provide electrical equipment for junction in which electronic parts, a board and so forth are hermetically sealed to implement waterproofing and vibration isolation measures, and also provide a method of manufacturing the electrical equipment for junction.
Still another object of the present invention is to provide electrical equipment for junction that is simplified in structure to reduce costs, and also provide a method of manufacturing the electrical equipment for junction.
The electrical equipment for junction and the method of manufacturing the same according to the present invention have the following advantages. The electrical equipment for junction has electronic parts tightly joined in the state of being housed with covers made of an aluminum alloy or the like. Therefore, the electrical equipment can be reduced in size and weight. Further, the peripheral edge of the covers is completely hermetically sealed to seal the electronic parts and so forth. Therefore, entry of water is completely prevented, and the structure is effective and excellent in heat dissipation and vibration isolation properties. Further, because the electrical equipment for junction has a simplified structure, it is possible to employ a manufacturing method of high productivity, e.g. an injection molding process, and hence possible to realize a reduction in cost of the electrical equipment. Employing the electrical equipment contributes to reduction in cost as well as weight of products such as automobiles.    Patent Document 1: Japanese Patent Application Publication No. Hei 11-308733    Patent Document 2: Japanese Patent Application Publication No. Hei 10-4274